Hyphal transport by a vesicular-arbuscular mycorrhizal fungus of N applied to the soil as ammonium or nitrate

A. Johansen, I. Jakobsen, E.S. Jensen

    Research output: Contribution to journalJournal articleResearch

    Abstract

    Transport of N by hyphae of a vesicular-arbuscular mycorrhizal fungus was studied under controlled experimental conditions. The N source was applied to the soil as (NH4+)-N-15 or (NH3-)N-15. Cucumis sativus was grown for 25 days, either alone or in symbiosis with Glomus intraradices, in containers with a hyphal compartment separated from the root compartment by a fine nylon mesh. Mineral N was then applied to the hyphal compartment as (NH4+)-N-15 or (NO3-)-N-15 at 5 cm distance from the root compartment. Soil samples were taken from the hyphal compartment at 1, 3 and 5 cm distance from the root compartment at 7 and 12 days after labelling, and the concentration of mineral N in the samples was measured from 2 M KCl extracts. Mycorrhizal colonization did not affect plant dry weight. The recovery of N-15 in mycorrhizal plants was 38 or 40%, respectively, when (NH4+)-N-15 or (NO3-)-N-15 was applied. The corresponding values for non-mycorrhizal plants were 7 and 16%. The higher N-15 recovery observed in mycorrhizal plants than in non-mycorrhizal plants suggests that hyphal transport of N from the applied N-15 sources towards the host plant had occurred. The concentration of mineral N in the soil of hyphal compartments was considerably less in mycorrhizal treatments than in controls, indicating that the hyphae were able to deplete the soil for mineral N.
    Original languageEnglish
    JournalBiology and Fertility of Soils
    Volume16
    Issue number1
    Pages (from-to)66-70
    ISSN0178-2762
    DOIs
    Publication statusPublished - 1993

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